Batteries are employed extensively in this country and abroad for automobiles, home uses, industrial uses, recreational uses, and military uses. A battery is normally tested by measuring its voltage output without a load. If the voltage is below a predetermined value, and the voltage characteristics of the battery with respect to the battery's capacity are known, one can determine whether the battery has sufficient capacity to perform a desired function. A more accurate indication of the battery's condition can be determined by noting the voltage drop of the battery under a load. A well-charged battery will experience only a slight voltage drop under a load, whereas a depleted battery will undergo a significant voltage drop under a load. For a wet-cell battery, the work capacity of the battery can frequently be determined by measuring the specific density of the electrolyte.
A dry-cell battery does not have a reservoir liquid electrolyte; thus, its capacity cannot be determined by taking specific gravity measurements. In addition, voltmeters are expensive, as are devices for measuring the voltage output of a battery, both under a load and under no load. Accordingly, most batteries are purchased or used without the purchaser/user knowing the true condition of the battery.
Recently, the manufacturer of DURACELL-brand batteries has been date-marking its packages to indicate by which date the battery should be in use. Although this date-stamping may be of some benefit to purchasers, it does not tell the purchaser the actual condition of the battery. Moreover, date-stamping of the package does not include date-stamping of the battery; thus, the purchaser has no idea of the use-date of a particular battery once it has been removed from the package.
Our related U.S. patent application identified above discloses a flashlight with a built-in battery tester having a voltmeter, ammeter, or visual-indicating chemical or LED cell to indicate when the battery's voltage output is above or below a predetermined value.
Flashlights, portable lanterns, portable radios and television, cameras, video recorders, portable dictating machine, and the like are used extensively in this country and abroad. Almost every home and business has at least one flashlight or portable lantern and a radio. Many home and businesses have numerous devices, such as recorders, portable radios and televisions, video recorders, calculators, cameras, and the like, which utilize batteries for their energy source. Some of the devices, such as flashlights, are used on an infrequent basis, that is, during an emergency situation where there has been a power failure or when it is not convenient to use a light source powered by conventional household current, such as for outdoor use or use in an unlighted attic or crawl space. Other devices, such as portable radios, are used extensively. The majority of these battery powered devices use dry-cell nonrechargeable batteries. Nonrechargeable alkaline batteries sold under the trademarks EVEREADY, DURACELL, RAY-OVAC, and the like, have a number of advantages over rechargeable batteries. On a weight-to-weight and volume-to-volume basis, the alkaline battery can supply three to four times the wattage of a rechargeable battery. In addition, nonrechargeable dry-cell rechargeable batteries put out a higher voltage than dry-cell rechargeable batteries. Many dry-cell rechargeable batteries, even if not in use, have to be periodically charged to keep the batteries from falling below a defined charge level to prevent permanent damage to the batteries. Alkaline batteries, which are used frequently, can have a shelf or storage life of from three to five years. During this period, no maintenance of the battery is required. In contrast, most rechargeable batteries wet-cell and dry-cell will completely discharge within six months or less of their last recharge.
Most individuals test their batteries by turning on the device in which the batteries are installed. If the device operates, the individual is normally satisfied that the batteries are operational. Some individuals will test the batteries on a battery tester to determine the condition of the batteries. Some individuals will even test the batteries under both loaded and unloaded conditions to measure the voltage drop. Although it is not complicated to test batteries, it is time consuming to disassemble a device, remove the batteries, test the batteries, and, if they pass the test, reinstall the batteries in the device. It is normally not possible to test new batteries at the time of purchase because of the battery protective packaging.
Accordingly, it is the object of the present invention to provide an improved battery having a built-in battery-strength indicator which permits one to immediately determine the battery's strength or condition. Thus, with the improved battery of the present invention, a user can quickly and effortlessly determine the strength or condition of a battery. When a batter is easily tested, as the battery of the present invention, the user of the battery is more likely to routinely check the condition of the battery.